∞ generated and posted on 2016.08.22 ∞
The speed with which a single example of one thing, on average, converts into a single example of another thing.
Thing A, for example, might fall apart into thing B at some rate that is based on the instability of A. Alternatively, you as found in place X (e.g., home) might change location to place Y (e.g., work or school) at some rate that is based on distance, traffic, and speed limits (and/or how fast you can walk or ride). But the timer will not begin until you have initiated to process of going. More complicated, thing A might have an affinity for thing B, resulting in the formation of thing C at some rate that begins once those two items have been brought together (or, in the case of molecules, have collided).
Upon meeting another individual for the first time, how long until you end up arranging to get together for a second meeting? This will depend on how much you appreciate that other individual, how shy you are, how much they appreciate you, how well you already know each other, etc. But if everything just clicks, then chances are that second get together will be quite a bit sooner than if there is no "attraction" at all (in which case your getting together again may never occur). Rates thus are a function how fast things happen, and rate constants describe how fast things happen once the potential for them to happen, such as molecules having collided, has begun.